I wanted to share with you my custom made ISR modification on my 1999 SR5 4-Runner. I think it looks neat and I love the sound.
After I figured out what I was going to do it was a piece of cake. I read many posts in regards to the ISR using PVC pipe and steel tubes. I wanted to make this modification with parts that anyone could purchase on the web. I am a plastics engineer so I also wanted to leverage my knowledge of these materials.
Part 1 of this post covers the general description and parts, part 2 describes the modification in more detail and part 3 has the pictures.
After a lot of search I finally found a tube 2.5” i.d. and 2.75 o.d. This I found at McMaster-Carr (www.mcmaster.com
), part #1989T21 for $22.56. This is a tube made out of Delrin plastic, and it is sold in 6” pieces. You can take the tube right out of the box and plug it on the IS place. I went a little further, but it is not required, and painted the tube with black high-temp engine paint (part 7614T418 from McMaster-Carr). The tube is made out of Delrin. Delrin is a polyacetal (POM) plastic with better temperature resistance than PVC. Its chemical resistance is good enough for the typical stuff around the engine bay. Delrin is actually used for fuel connections in motorcycles. And for those of you skeptical about plastics, keep in mind that the original IS is made out of Polypropylene plastic, which has a much lower temperature resistance. Plus the IS is closer to the engine, so it gets even hotter. As a warning, keep Delrin away from chlorine.
Depending how sophisticated you want this modification to be, you can do the tee connection from the front of the intake manifold for the vacuum hose that has been talked to death on this forum. I first tried this way and work fine. However, I wanted to keep the vacuum connected before the TB as stock. What I did is use a nipple with a 1/8” NPT thread on one end and a ¼” barb on the other. I drilled the respective hole on the Delrin pipe, tapped it and screwed the nipple. Then purchase a universal vacuum hose and connected it from the nipple to the original connection on the engine.
I was lucky to have a 1/8” NPT nipple and tap at my company. You won’t find these on your regular Home Depot or auto parts store. However, you can find these on specialty stores that sell pneumatic equipment. I used Pneumadyne, which is an excellent source for all type of miniature connectors and fittings. I used some of these connectors for a project here at work so I had them lying around.
EDIT: you may be able to use other nipple with a different thread or fitting. I used this specific one because it's what I had handy. Stick with as a small tap as possible. This will limit the amount of intrusion into the pipe, and improve the thread grip.
List of parts, cost and where to find them:
6” Delrin tube, 2.5” i.d., 2.75” o.d., $22.56
, part #1989T21
High temp engine spray paint black, $5.43
, part # 7614T418
1/8” NPT tap, $6.94, http://www.aquaticeco.com/index.cfm/.../9863/cid/3076
EDIT: you can find the tap at McMaster-Carr as well,part # 2525A112, $5.20
1/8” NPT x ¼” fitting, $0.75 ea. (I think there is a 25 piece minimum order)
, click on the “not a distributor” link. Search for the part number, EB60-1/16
2' universal vacuum tube, $3.50
Any auto parts store
Disclaimer: my intention is this post to be a suggestion but I am not responsible if it does not work in your vehicle. So fat it works great for me!